Re: [PATCH] powerpc/perf: Fix memory allocation for core-imc based on num_possible_cpus()
From: Michael Neuling <hidden>
Date: 2018-05-11 23:45:37
On Fri, 2018-05-11 at 19:13 +0530, Anju T Sudhakar wrote:
Currently memory is allocated for core-imc based on cpu_present_mask, whi=
ch
has bit 'cpu' set iff cpu is populated. We use (cpu number / threads per cor=
e)
as as array index to access the memory. So in a system with guarded cores, since allocation happens based on cpu_present_mask, (cpu number / threads per core) bounds the index and le=
ads
to memory overflow. =20 The issue is exposed in a guard test. The guard test will make some CPU's as un-available to the system during =
boot
time as well as at runtime. So when the cpu is unavailable to the system during boot time, the memory allocation happens depending on the number of avail=
able
cpus. And when we access the memory using (cpu number / threads per core)=
as
the index the system crashes due to memory overflow. =20 Allocating memory for core-imc based on cpu_possible_mask, which has bit 'cpu' set iff cpu is populatable, will fix this issue. =20 Reported-by: Pridhiviraj Paidipeddi <redacted> Signed-off-by: Anju T Sudhakar <redacted>
Thanks, this should be:=20 Cc: <redacted> # 4.14
quoted hunk ↗ jump to hunk
--- arch/powerpc/perf/imc-pmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) =20diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c index d7532e7..75fb23c 100644 --- a/arch/powerpc/perf/imc-pmu.c +++ b/arch/powerpc/perf/imc-pmu.c@@ -1146,7 +1146,7 @@ static int init_nest_pmu_ref(void)=20 static void cleanup_all_core_imc_memory(void) { - int i, nr_cores =3D DIV_ROUND_UP(num_present_cpus(), threads_per_core); + int i, nr_cores =3D DIV_ROUND_UP(num_possible_cpus(), threads_per_core); struct imc_mem_info *ptr =3D core_imc_pmu->mem_info; int size =3D core_imc_pmu->counter_mem_size; =20@@ -1264,7 +1264,7 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr, st=
ruct
device_node *parent, if (!pmu_ptr->pmu.name) return -ENOMEM; =20 - nr_cores =3D DIV_ROUND_UP(num_present_cpus(), threads_per_core); + nr_cores =3D DIV_ROUND_UP(num_possible_cpus(), threads_per_core); pmu_ptr->mem_info =3D kcalloc(nr_cores, sizeof(struct imc_mem_info), GFP_KERNEL); =20